Eleven years after the discovery of the human immunodeficiency virus.

The nucleotide sequence of the human immunodeficiency virus (HIV-1) gp120 variable region (V3) was obtained by sequencing the product of the Polymerase Chain Reaction (PCR) amplification of seven HN-I Mexican isolates from patients who had been infected either sexually or through blood products. Mexican isolates showed a 61.4% homology between them and three viral subtypes were demonstrated One of these corresponds to three sexually infected patients, another to two hemophiliac patients infected through blood products or transfusions and the third subtype to either sexually or blood infected patients. The latter shows a great similarity to the HTLVIIIb/LAV prototype strain. Antigenic profiles of this region show at feast three neutralization patterns for these isolates as well as one virus that does not have a high predictive value epitope in the V3 region. Our data show that Mexico has a high heterogeneity of HN-I circulating strains, similar to that reported in other regions of the world.